We do know that a lot of users are successfully using Linux distro's on their units. If the problem persist after trying the BIOS update and since we provide limited support for that operating system, my recommendation in order to get further assistance on this matter will be to check the Linux forums for peer to peer assistance, in there you should be able to get more suggestions on this subject:https://ubuntuforums.org/forumdisplay.php?f=326

Intel doesn’t officially provide support or drivers for Linux* please check the following url for further information: https://www.intel.com/content/www/us/en/support/boards-and-kits/intel-nuc-boards/000005628.html. This doesn’t mean that Linux or any other operating system different than Windows* will not work on this device, it means that we don’t do official validation or testing and in addition to that, the Intel® NUC Kit NUC6CAYS comes with Windows 10 Home (64-bit) Pre-Installed.

I would recommend that you post this question to a Linux community, they may be able to help you with that.